1. Field of the Invention
This invention relates generally to a method for removal of organometallic and organosilicon residues and damaged oxides created in processing of semiconductor wafers, and more particularly to a method for selective removal of such residues and damaged oxides using anhydrous ammonium fluoride in a polyhydric alcohol solution.
2. Brief Description of the Prior Art
Hydrogen fluoride has been widely used in etching processes for patterning films on semiconductor wafers. Hydrogen fluoride has very high etching rates, and therefore a number of alternatives to hydrogen fluoride have been developed. Kinsbron et al., U.S. Pat. No. 4,343,677, discuss film patterning and disclose an etching solution which uses buffered ammonium fluoride/hydrofluoric acid in a molar ratio of about ten to one, mixed with a suitable solvent such as ethylene glycol. Gajda, U.S. Pat. No. 4,230,523, discloses an etchant comprised of a solution of hydrogen fluoride dissolved in organic solvents such as glycerine or another polyhydric alcohol. The etchant is used for etching silicon dioxide while not attacking silicon. Gajda requires that the solution be free of unbound water and ammonium fluoride. Maeda et al., U.S. Pat. No. 3,979,241, teach an etching liquid with ammonium fluoride or an alkali fluoride dissolved in a polyhydric alcohol, such as ethylene glycol, polyethylene glycol, and glycerine. The etching solution is used for selectively etching silicon dioxide or silicon nitride on a semiconductor wafer.